Strain sensors are used to measure load. The signal from the strain sensor is then processed to represent a load value. Load measuring in a bearing is known e.g. from DE 102 50 340, where a load measuring bearing comprises strain gauges that are mounted as a thick film on one of the bearing rings. The bearing ring is formed with a slot in which during heat treatment of the ring the thick film with the strain gauge is burned.
Such an arrangement has the disadvantage that the bearing ring needs to be a stiff element to properly support the rolling elements, with as little misalignment of the rolling elements under load as possible. Because of this stiffness of the bearing rings the resolution of the strain-gauges is very limited. As a result only forces that act in the weakest direction of the bearing ring are measurable.